1. Field of the Invention
The present invention relates to a color image recording material of mono-sheet type which forms full color images of excellent shelf stability and high resolution utilizing photo-curable microcapsules.
2. Related Art Statement
Recording materials which form color images using photo-curable microcapsules are disclosed, for example, Japanese Patent Kokai (Laid-Open) Nos. 59-30537 (U.S. Ser. No. 339917), 61-275742, 62-187836, 62-39844 and 62-39845.
As one of the embodiments disclosed in Japanese Patent Kokai (Laid-Open) No. 59-30537 (U.S. Ser. No. 339917) there is a process of forming images by transferring a color precursor from a transfer sheet comprising a support and, provided thereon, microcapsules containing color precursors of cyan, magenta and yellow and a photosensitive resin to an image receiving sheet having a layer of a developing material. Another embodiment disclosed in the above patent publication is use of a transfer sheet comprising a support and, provided thereon, microcapsules containing color precursors of cyan, magenta and yellow and a photosensitive composition different in sensitive wavelength. The exposed microcapsules-coated side of the transfer sheet and the developing material-coated side of the image receiving sheet are brought into close contact with each other and applied with pressure to transfer the color precursor, whereby a complete color image can be obtained by one pressure transfer. Alternatively, the so-called "self-contained" technique can be used in connection with the above-mentioned embodiment. For example, under a layer of photosensitive microcapsules containing a color pressor a layer of a developing material is provided as another layer and an image can be formed on a support by a self type image formation. However, the color precursors used in the above patent publication are colorless electron donor type leuco dyes and are inferior in image shelf stability such as light resistance, fingerprinting resistance and solvent resistance. In the case of the process of forming images by transfer to image receiving sheet, the transfer sheet becomes useless after recording and this requires maintenance for disposal of the waste transfer sheet and further this process is not economical. Moreover, according to the first embodiment of the above patent publication, exposures must be done three times for respective cyan, magenta and yellow and accordingly transfer must be carried out three times and hence color images of high resolution are difficult to obtain owing to the problem of deviation in the position of images. Further, in the case of self type, when sensitivity to visible light region is imparted, background is colored. Therefore, only photosensitive composition sensitive to ultraviolet region can be used to keep the background in white color.
The recording material disclosed in Japanese Patent Kokai (Laid-Open) No. 61-275742 is characterized in that it has at least a photosensitive silver halide, a reducing agent, a polymerizable compound and a color image forming substance on a support and at least the polymerizable compound and the color image forming substance are enclosed in the same microcapsule. This process has the advantages that the material can have a sensitivity to visible light and besides has high sensitivity because photosensitive silver halide is used, but has the defect that it is expensive.
The recording material disclosed in Japanese Patent Kokai (Laid-Open) No. 62-187836 filed by the present inventors is a color image recording material which comprises a support and, provided thereon, multilayers comprising at least two of (a) a layer of microcapsules containing mainly a photo-curable resin or microcapsules containing mainly a photo-curable resin and a coloring agent, (b) a layer of a light proofing white material and (c) a layer mainly composed of a coloring agent, said lightproofing white layer mainly composed of lightproofing white material being provided directly or indirectly on a picture element layer comprising picture elements of two or more colors comprising microcapsules containing mainly a photo-curable resin and a coloring agent or coloring agents arranged in the form of stripe or mosaic. One embodiment of the invention disclosed in the patent publication includes a color image recording material which comprises a support on which is provided a picture element layer comprising picture elements of at least two colors comprising coloring agents arranged in the form of stripe or mosaic, on which are further provided a layer of microcapsules containing mainly a photo-curable resin and a lightproof white layer comprising a lightproof white material in succession. In this image recording material, colored dye or pigment which has been used for printing ink can be utilized and so the resulting image is very high in shelf stability, but in order to obtain a color image of high resolution, the size of the picture elements arranged in the form of stripe or mosaic must be smaller than 1/10 (mm/dot), preferably 1/20 (mm/dot) and this is difficult by ordinary printing technique. Furthermore, in this process, positions of the picture elements of cyan, magenta and yellow must be read also at the time of recording and with reduction of the size of the picture elements this reading becomes difficult.
The recording material disclosed in Japanese Patent Kokai (Laid-Open) Nos. 62-39844 and 62-39845 is a plain paper transfer type photosensitive and pressure-sensitive recording sheet which comprises combination of a plain paper with a coated paper comprising a support coated with microcapsules containing a photo-curable resin and a solution of colored dye or pigment dissolved or dispersed in an organic solvent. However, this is also operationally and economically not preferred in that a transfer sheet is used.